Geo, I tried not to write that post to be confusing. I had first written "a factory that can produce anything", but then changed it to what it says now.
Anyways, my point was not that we could not make an automated factory, but that we could not make an automated factory capable of producing whatever we needed it to at any particular moment in time. Even it the factory was capable of retooling itself, it would still need to do so to produce something different than what it was original set up to produce.